COMPARISION OF T1 FAT SUPPRESSED (FS) POSTCONTRAST AND T2 FLUID ATTENUATED INVERSION RECOVERY (FLAIR) POSTCONTRAST SEQUENCES IN EVALUATION OF INTRACRANIAL LESIONS

Abstract

Background: T2 FLAIR postcontrast (PC) sequence can provide additional information with regards to evaluation of pyogenic abscesses, perilesional edema & intracranial tumors. T2 FLAIR PC is also better at delineating meningeal and cranial nerve diseases1. T2 FLAIR PC sequence provides several advantages over T1 FS PC imaging, which includes suppression of the cerebrospinal fluid (CSF) signal, no or minimal enhancement of blood vessels, reduction of phase-shift artifacts derived from enhanced blood vessels or dural sinuses, and better detection of peritumoral edema making lesions more conspicuous1. Therefore, T2 FLAIR PC sequence could be considered as an adjunct over T1 FS PC sequence in evaluation of various intracranial pathologies2. Purpose: The objectives of the study were to determine if T2 FLAIR postcontrast sequence is superior to T1 FS postcontrast sequence in evaluation of intracranial lesions and to compare the utility of T2 FLAIR postcontrast sequence when combined with T1 FS postcontrast sequence in evaluation of intracranial lesions. Material and Methods: This prospective observational study was conducted over a period of eighteen months from January 2019 to June 2020 on 64 patients who underwent plain and gadolinium enhanced MRI brain. Baseline data and MRI sequences including T1 and T2 axial, T1 sagittal, T2 coronal, FLAIR axial, diffusion weighted imaging (DWI), and susceptibility weighted imaging (SWI) were accuqired. Postcontrast sequences obtained were T1 FS XV (axial, coronal and sagittal), T2 FLAIR, and VIBE. Final diagnosis will be obtained by comparing T1 FS postcontrast & T2 FLAIR postcontrast sequences. Results: There were total of 64 cases with predominantly male patients. Out of 64 cases, intra-axial pathology outweighed extra-axial and meningeal pathologies. In this study, T1 FS PC sequence showed better characterization of intra-axial lesions in 11 cases, extra-axial lesions in 6 cases and meningeal enhancement in 3 cases when compared to T2 FLAIR PC sequence. T1 FS PC sequence showed equal enhancement of intra-axial lesion in 1 case, extra-axial lesion in 2 cases and meningeal enhancement in 1 case when compared to T2 FLAIR PC sequence. T2 FLAIR PC sequence showed better characterization of intra-axial lesions in 28 cases, extra-axial lesions in 7 cases and meningeal enhancement in 17 cases when compared to T1 FS PC sequence. Conclusion: In our study, we concluded that T2 FLAIR PC sequence acts as an adjuvant to T1 FS PC sequence and plays a major role in characterization of the lesion. Diagnostic accuracy has increased significantly with addition of T2 FLAIR PC sequence to routine MRI protocol. Our study showed that there is significant contribution of T2 FLAIR PC sequence in assessing subtle lesions, extent of perilesional edema, solid component enhancement and in diagnosing meningeal pathology with few limitations.